Safety electric switch



Jan 8, 1924.

R. F. POL! SAFETY ELECTRIC SWITCH Filed Jan. 18 19?.2

2 Sheets-Sheet l RAPHAEL F POI-l SWO: "121 Jan 8, 1924.

R. F. POLI SAFETY ELECTRIC SWITCH 1.922 2 Sheets-Sheet 2 Filed Jan. 18

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Patented Jan. 8; 1924.

UNITED STATES RAPHAEL I. POLL OI CAMP SCHUIWAY, COLORADO.

SAFETY ELECTRIC SWITCH.

Application Med January 18, 1928. Serial No. 618,875.

To all whom it may concern:

Be it known that I, RAPHAEL F. Pom, a citizen of the United States,residin at Camp Schumway, in the county of norfano and State ofColorado, have invented certain new and useful Improvements in SafetyElectric Switches, and I do declare the following to-be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same,reference bein d to the characters 0 reference marked thereon, whichform a part of this specification.

This invention relates to electric switches of the type in which thetranslating device circuit can only beconnected or disconnected whilethe switch is open.

In mines, factories and other places wherea machine is to be employed indifferent places it is common to provide a set of feeder mains extendingthroughout the mine or factory and to connect the machine to the feedersat the most convenient place. I shall describe my invention as employedin coal mining, as I intend to use it in this relation although, asindicated above, it can be used in other places.

In coal mines a set of feeder wires are run through the main galleriesfor convenience in making connection to the electric drills,undcrcutters or other machines used in the mining operation. Themachines are ordinarily provided with a long cable whose free. end isprovided with clips or other means for making connection to the feedercircuit. It has frequently happened that when the o erator connects theclips to the feeders t ere 1s ashort circuit on the line to the machine,or the machine may be of large current capacity and connected to theline. In either case there is a heavy flow of current as soon as theinitial contact is made which results in a. heavy are which temporarilyand sometimes permanently blinds the operator. In the same manner, ifthe operator should attempt to disconnect the conductors from thefeeders, before the translating device is disconnected, an arc will beformed often with disastrous results.

It is a further ob'ect of this invention to provide a switch w ich canbe opened and closed without danger of the operator coming in contactwith live parts. The above ob ects and others, which will appear as hadto the accompan ing draw the description proceeds, are attained by aconstruction which I will now describe, reference for this purpose beinghad to the accompanying drawing, in which:

Fig. 1 IS a horizontal section through a portion of a coal mine andshows the rela tive location of the feeder circuit safety switch and theelectric drills or other apparatus employed.

Fig. 2 is a central longitudinal section of my safety switch.

Fig. 3 is a horizontal section taken on line 3-3, Fig. 2.

Fig. 4 is a horizontal section taken on line 3-3, Fig. 2 and lookingupwardly.

Fig. 5 IS a transverse vertical section taken on hline 55,. Fig. 2,looking toward the ri t.

ig. 6 is a transverse vertical section taken .on line 6-6, Fig. 2,looking towards the left.

Fig. 7 is a plan view of the attachment plug with the upper pomionthereof broken away to better show the construction; and

Fig. 8 is a transverse section taken on line 8-8, Fig. 7

- The same reference numbers will be used to designate the same partsthroughout the several views.

Numeral 1 represents a three wire feeder line which is run along thegalleries of the mine, 2 represents the side walls and 3 the rooms inwhich coal is being mined, while 4 indicates an electric (hill or othermining machine which is electrically operated. A- flexible cable 5extends from the ma:- chine 4 to the safety switch 6 and is provided atits free end with a plug 7 by means of which the conductor 5 isconnected to the switch terminals.

My safet switch consists of a box of woo meta or any other suitablematerial. This box has a. bottom 8 and a cover 9 hinged to one end ofthe box by means of hinges 10 (Fig. 2). To the inside of the bottom Isecure an insulatin switch base 11 which is held in place y means ofscrews or bolts 12. Secured to the base 8 near each corner thereof areinsulating guide posts 13. The base member 11 is preferably of such sizethat the corners have to be notched for the accommodation of the guideposts. Secured to, the switch base 11 are a plurality of pairs ofcontact clips 14 which may be of the type shown in Fig. 6 or of anyother usual type which is adapted to receive a switch blade. Each clipit at the left hand end of the box has electrically connected theretoconductor torurinals 15 secured to the ends of conductors 16 whose otherends are electrically connected with the feeder circuit 1. The switchclips it in the right hand end of the be}: 2 and 3) have electricallysecured thereto-tubular soclret members 17 having daring ends 18 asclearly shown in l ig 26 These sockets serve to receive and formelectrical contact with the plug members of the connector plug 7 in themanner hereinafter described. The movable part of the switch consists ofan insulating plate 19 which has notches 20 cut out of each corner forthe reception of the guide posts it (Fig. d). To the upper side ofmember 19 li'secure a bracket 21 to which the rod 22 is connected by anysuitable means, l have shown this red as made of metal as it well may beas it is electrically insulated from all live terminals, but where it isdesired, it may be made from bakelite hard rubber. fibre or otherinsulating ma terial. Secured to the outer surface oi the cover 9 is atubular metal member 22 which has two diametrically opposed slots 23provided at their bottom with notches 2d. Within the tubular member 22and surrounding the rod 21 is a coil compression spring 25 (Fig. 2). A.in 26 extends transversely through the rod 21 and has its ends extendinginto slots 23. The upper end of spring 25 abuts the pin 26 and tends tohold the plate 19 and associated parts in the full line position shownin'l igs. 2., 5 and. d. The upper end of the rod 21. is provided with asphericl hand grip 27 of in-- sulating material. on it is desired toclose. the switch rod 21 is moved downwardly until pin 26 comes oppositenotches 2t, and it is then slightly rotated so that the ends of pin 26engage the shoulders of the notches 242 and hold the switch closedagainst the action of spring 26. A slight rotation of rod 21 so as tomove the pins 26 out of notches 2%, permits the 'switch to open with asnap. Secured to the lower side ot the movable insulating plate 19 are anumber of knife blade connectors 28 which are secured thereto by clips29 in the manner shown in Fig. 6 or in any other substantial manner.When the switch is in closed position indicated by dotted lines in Fig2, knife blades 28 connect members of corresponding pairs of clips 14%.The

cover 9 may be locked in place by a hasp and staple cooperating with anordinary padlock as in icated by numeral 32, in Fig. 2.,

Gonnectm-n between the switch and the cable 5 is made by means of a plugmain bar t which, a res wire installation account such as shown, hasthree plug contacts 3i and 32 which fit into suitable grooves in theadjacent surfaces of the two coopera ing members 33 and 34 in the mannerclearly shown in Figs. 2 and 7. The two outside plug members 31am curvedat their inner ends, as shown in Fig. l, and consequently not be pulledout but the center plug 32 is straight and is therefore provided with anenlargement 35 which pr vents longitudinal movement. Plug 7 has a"handle portion 36 which permits it to be conveniently manipulated.

- The plugs 31 and 32 are spaced the same distance apart as tubularsockets l?" and hushed openings 3? are provided in the end wall of theswitch box, through which openings the plugs. may be inserted and theends thereof introduced into the tubular. contacts 17. lit is essentialthat the plugs cannot be connected to or removed. from the connectors 17while the switch is in closed positionand to accomplish this result lprovide the following means:

To the end of the movable insulating switch member 19 l secure adownwardly projecting plate 38 of insulating material. Plate 38 extendsdownwardly such a distance that when the switch is in closed po sitionthe lower edge will almost reach the upper surface of the switch base ll(see dotted line position in Fig. 2). 'fhe lower edge of plate 38 hasthree notches 39 correspending to each of the tubular sockets ll. Thesenotches are cl such size that plugs 31 and 32 can pass through them.line or all of the plugs are provided near their ends with anenlargement 40 which is so large that it will not pass through thenotches 39. ll the switch is closed the plug cannot be connected to thelive tubular connectors 17 becausethe enlargement will engage the plate38 in the manner indicated in Fig. 2 and in a like manner the plu cannotbe withdrawn as long as the switc is closed as the enlargement is thenon the inside of late 38 and prevents withdrawal. My switc is thereforeso constructed that the plug can be inserted and removed only while theswitch is open. This insures that the operator cannot be injured b anare as he connects or disconnects the p ug. After the plug is insertedthe switch is closed by a downward pressure on the handle 2"? and lockedin position by a slight turn.

From the above description it will be apparent that l have invented aswitch that is especially adapted for use in mines and otherplaces wherepower is taken from various points along a main feeder line as theconnection to the translating device cannot be made while the switch isclosed Having now described my invention what I claim is: v

i. it switch comprising in coination a lilil switch box; a coverhingedly connected thereto; an insulating switch base secured to thebottom of the box; a plurality of contact clips secured to said base inairs; conductors secured to one member 0 each pair, the other clips ofeach pair having a. tubular connector secured thereto, one end of thebox having openings registering with the tubular connections, saidopenings being adapted to receive. plugs which connect with the tubularconnectors; an insulating switch base movably mounted in said box;conductors mounted on said base and adapted to connect pairs of contactclips; resilient means cooperating with the movable switch member andtending to hold the switch in open position; a rod extendin through theswitch box and having one end connected to the. movable insulated basewhereby'the same may be moved from 0 en to closed position; a plate ofinsulating material secured to one end of the movable plate and adaptedto obstruct the passage from said openings to said tubular connectorswhen the switch is in closed position; and openings in the lower edge ofsaid plate.

2. A switch comprising, in combination, a switch box having a hingedcover; a switch base of insulating material secured to the bottom ofsaid box; a pluralit of pairs of contact clips secured'to said ase,

corresponding cli s of each pair having conductors secure thereto, theother clips of each pair having tubular connectors secured thereto, theend of the box nearest the tubular connectors having openings thereinthrough which plug members ma be inserted for connection with thetubular connectors; a plurality of guide members secured to the switchbottom and extending upwardly in parallel relation; an insulating memberhaving means for cooperating with said guides; means secured to theinsulating member and extending throu h the cover of the box-for movingthe insu ating member; resilient means comprising a spring for normallyholding the insulating member in open position; a plurality of knifeblade connectors secured to the under side of the insulating member andadapted to connect the clips of each pair; means for holdin the switchclosed against the action of said spring; and a plate of insulatingmaterial secured to one end of the movable insulating member, said platebeing adapted to obstruct the passageway from the tubular connectors tothe openings in the end wall so as to prevent the insertion of a plugconnector, said plate having a number of notches on its lower edge.

In testimony whereof I aflix my signature.

RAPHAEL F. POLI.

